CN117461159A - Secondary battery, battery module, battery pack, and power consumption device including the same - Google Patents
Secondary battery, battery module, battery pack, and power consumption device including the same Download PDFInfo
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- CN117461159A CN117461159A CN202280040386.1A CN202280040386A CN117461159A CN 117461159 A CN117461159 A CN 117461159A CN 202280040386 A CN202280040386 A CN 202280040386A CN 117461159 A CN117461159 A CN 117461159A
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- Prior art keywords
- secondary battery
- positive electrode
- optionally
- electrolyte
- solvent
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- 238000001914 filtration Methods 0.000 description 1
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- ZYMKZMDQUPCXRP-UHFFFAOYSA-N fluoro prop-2-enoate Chemical compound FOC(=O)C=C ZYMKZMDQUPCXRP-UHFFFAOYSA-N 0.000 description 1
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- MHCFAGZWMAWTNR-UHFFFAOYSA-M lithium perchlorate Chemical compound [Li+].[O-]Cl(=O)(=O)=O MHCFAGZWMAWTNR-UHFFFAOYSA-M 0.000 description 1
- 229910001486 lithium perchlorate Inorganic materials 0.000 description 1
- 229910001496 lithium tetrafluoroborate Inorganic materials 0.000 description 1
- QSZMZKBZAYQGRS-UHFFFAOYSA-N lithium;bis(trifluoromethylsulfonyl)azanide Chemical compound [Li+].FC(F)(F)S(=O)(=O)[N-]S(=O)(=O)C(F)(F)F QSZMZKBZAYQGRS-UHFFFAOYSA-N 0.000 description 1
- IGILRSKEFZLPKG-UHFFFAOYSA-M lithium;difluorophosphinate Chemical compound [Li+].[O-]P(F)(F)=O IGILRSKEFZLPKG-UHFFFAOYSA-M 0.000 description 1
- MCVFFRWZNYZUIJ-UHFFFAOYSA-M lithium;trifluoromethanesulfonate Chemical compound [Li+].[O-]S(=O)(=O)C(F)(F)F MCVFFRWZNYZUIJ-UHFFFAOYSA-M 0.000 description 1
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- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 1
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Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Abstract
The secondary battery (5) comprises a positive electrode plate, a negative electrode plate, a separation film and electrolyte, wherein the positive electrode plate comprises a positive electrode active substance, the positive electrode active substance comprises a core and a coating, and the manganese content of the core is more than or equal to 25 percent based on the weight of the core; the coating is coated on the surface of the inner core and comprises one or more of oxides, hydroxides or oxysalts of an element X, wherein the element X is selected from one or more of Al, B or P, and the weight ratio of the coating to the inner core is 1:5-100, and is optionally 1:16-100; the electrolyte comprises a first solvent selected from one or more of fluorocarbonate, fluorocarboxylate, fluorosulfone, fluoroether or fluorobenzene. The secondary battery has good electrical storage performance and cycle performance. Related battery modules, battery packs, and power consuming devices are also provided.
Description
The present disclosure relates to the field of lithium batteries, and more particularly, to a secondary battery, a battery module, a battery pack, and an electric device including the secondary battery.
In recent years, as the application range of lithium ion batteries is wider and wider, more and more requirements are put on the performance of secondary batteries, and one of them is that the secondary batteries are expected to have good storage performance and cycle performance, especially under high-voltage working conditions. Therefore, how to provide a secondary battery with good storage performance and cycle performance under high voltage conditions is still a technical problem that the skilled person needs to solve.
Disclosure of Invention
The present application has been made in view of the above-described problems, and an object thereof is to provide a secondary battery having significantly improved storage performance and cycle performance under high-voltage operation.
A first aspect of the present application provides a secondary battery comprising a positive electrode tab, a negative electrode tab, a separator, and an electrolyte, wherein
The positive electrode plate comprises a positive electrode active material, wherein the positive electrode active material comprises a core and a coating, and the manganese content of the core is more than or equal to 25 percent based on the weight of the core; the coating is coated on the surface of the inner core and comprises one or more of oxides, hydroxides or oxysalts of an element X, wherein the element X is selected from one or more of Al, B or P, and the weight ratio of the coating to the inner core is 1:5-100, and can be 1:16-100;
The electrolyte comprises a first solvent selected from one or more of a fluorocarbonate, a fluorocarboxylate, a fluorosulfone, a fluoroether, or a fluorobenzene.
When the positive electrode active material and the electrolyte of the secondary battery meet the above conditions, the secondary battery has good stability, thereby being beneficial to improving the storage performance and the cycle performance of the secondary battery.
In any embodiment, optionally, the manganese ion dissolution coefficient k of the positive electrode sheet is less than or equal to 0.035%, optionally k is less than or equal to 0.017%, more optionally k is less than or equal to 0.01%, and the manganese ion dissolution coefficient refers to the weight percentage of manganese ions in the electrolyte after the positive electrode sheet in a full charge state is stored at 60 ℃ for 48 hours together with the electrolyte (electrolyte injection coefficient is 5 g/Ah).
When the manganese ion dissolution coefficient of the positive electrode plate meets the conditions, the stability of the positive electrode interface can be obviously improved, the side reaction of the interface is reduced, the stability of the secondary battery is improved, and the storage performance and the cycle performance of the secondary battery are further improved.
In any embodiment, optionally, the static protection layer stability coefficient of the positive electrode sheet is 54% or less than or equal to e1 or less than or equal to 100%, optionally 70% or less than or equal to e1 or less than or equal to 100%, and more optionally 85% or less than or equal to e1 or less than or equal to 100%, where the static protection layer stability coefficient refers to a ratio of a content of element X remaining in a positive electrode film layer to a content of element X included in the positive electrode film layer when the positive electrode sheet is in an initial full-charge state after the positive electrode sheet in a full-charge state is stored together with the electrolyte at 60 ℃ for 48 hours.
When the stability coefficient of the protective layer of the positive electrode plate meets the above conditions, the stability of the secondary battery can be further improved, and the storage performance and the cycle performance of the secondary battery can be improved.
In any embodiment, optionally, the dynamic protection layer stability factor e2 of the positive electrode sheet satisfies: and the dynamic protection layer stability coefficient refers to the ratio of the content of the element X remained in the positive electrode film layer to the content of the element X included in the positive electrode film layer before the storage after the positive electrode plate in a full charge state is stored at 60 ℃ for 48 hours together with the electrolyte, wherein the e2 is more than or equal to 20% and less than or equal to 100%, the e2 is more than or equal to 50% and the e2 is more than or equal to 100% is selected.
When the dynamic protection layer stability coefficient e2 is within the above range, the secondary battery has better stability, which is beneficial to improving the storage performance and the cycle performance of the secondary battery.
In any embodiment, the content of element X in the positive electrode film layer is optionally 0.05% to 5.35%, optionally 0.1% to 1.61%, and more optionally 0.24% to 1.61%, based on the total weight of the positive electrode active material.
When the content of the element X in the positive electrode film layer is in the range, the direct contact between the core material and the electrolyte can be effectively reduced, the side reaction is reduced, and the dissolution of manganese ions is reduced, so that the storage performance and the cycle performance of the secondary battery are improved.
In any embodiment, optionally, the inner core is selected from LiM p Mn 2-p O 4 、LiN q Mn 1-q PO 4 Or Li (lithium) 1+t Mn 1-w L w O 2+t Wherein 0.ltoreq.p.ltoreq.1, 0.ltoreq.q.ltoreq.0.5, 0.ltoreq.t.ltoreq.1, 0.ltoreq.w.ltoreq.0.5, M, N, L each independently represent one or more of Ni, co, fe, cr, V, ti, zr, la, ce, rb, P, W, nb, mo, sb, B, al, si;
more optionally LiM p Mn 2-p O 4 Or Li (lithium) 1+t Mn 1-w L w O 2+t One or more of the following;
more optionally LiNi 0.5 Mn 1.5 O 4 、LiNi 0.5 Co 0.2 Mn 0.3 O 2 、Li 2 MnO 3 、LiMnPO 4 One or more of the following.
When the core material of the secondary battery is selected from the above types, it is advantageous to increase the energy density of the secondary battery, reduce the manufacturing cost, and reduce environmental pollution.
In any embodiment, the coating is optionally selected from the group consisting of alumina, boria, borates, i.e., A a+ x [BO 3 ] 3- y Phosphate, i.e. A a+ x [PO 4 ] 3- y Or aluminates, i.e. A a+ x [AlO 2 ] 1- z One or more of (a) and (b) thereofWherein a represents one or more of Li, na, K, rb, cs, mg, ca, ba, ni, fe, co, ti, al, cr, V, nb, W, wherein each compound is electrically neutral and a, x, y or z is selected from 1, 2 or 3;
can be selected from Al 2 O 3 、B 2 O 3 、Li 3 BO 3 、Li 3 PO 4 、Na 3 PO 4 Or LiAlO 2 One or more of the following.
When the coating is selected from the above materials, it is advantageous to reduce elution of transition metals and interfacial side reactions, thereby improving battery performance.
In any embodiment, optionally, the first solvent is selected from the group consisting of Wherein R is one or more of 1 、R 3 、R 5 And R is 13 Independently of one another selected from C 1 To C 6 Fluoroalkanes, R 2 、R 4 、R 6 、R 14 、R 15 And R is 16 Independently of one another selected from C 1 To C 6 Alkanes or C 1 To C 6 Fluoroalkanes, R 7 To R 12 Independently of one another selected from C 1 To C 6 Fluoroalkanes, fluorine or hydrogen, wherein R 7 To R 12 At least one of them is selected from fluorine or fluorinated alkanes, R 15 And R is 16 At least one of them is selected from C 1 To C 6 A fluoroalkane;
can be selected as One or more of the following.
In any embodiment, optionally, the electrolyte further comprises a second solvent selected from one or more of non-fluorinated carbonates, non-fluorinated carboxylates, non-fluorinated ethers, or non-fluorinated sulfones;
can be selected asWherein R is one or more of 1 ’、R 2 ’、R 3 ’、R 13 ’、R 14 ' and R 16 ' are independently selected from C 1 To C 6 Alkanes, R 4 ' and R 15 ' are independently selected from C 1 To C 6 Alkanes or hydrogen;
more preferably one or more of methyl ethyl carbonate, dimethyl carbonate, diethyl carbonate, ethylene carbonate, propylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, and propyl propionate.
When the first solvent and the second solvent are selected from the solvents, the solvents can form a special solvation structure with lithium salt in the electrolyte, which is beneficial to reducing side reactions of the solvents on the surfaces of the anode and the cathode and prolonging the service life of the secondary battery.
In any embodiment, the first solvent content y1 is optionally 10-100%, optionally 40-100%, more optionally 80-100%, based on the total weight of the first solvent and the second solvent.
In any embodiment, the second solvent content y2 is optionally 0-90%, optionally 0-60%, more optionally 0-20%, based on the total weight of the first solvent and the second solvent.
In any embodiment, optionally, the content y1 of the first solvent and the content y2 of the second solvent satisfy: y1/y2 is more than or equal to 0.66, optionally y1/y2 is more than or equal to 2.33, and more optionally y1/y2 is more than or equal to 4.
When the content of the first solvent and the second solvent is within the above-described range, it is advantageous to further improve the storage performance and the cycle performance of the secondary battery.
In any embodiment, optionally, the electrolyte further comprises a film forming additive selected from one or more of a chain or cyclic sulfate, a chain or cyclic sulfonate, a chain or cyclic carbonate, a polycyclic sulfate, or a polycyclic sulfonate;
can be selected as One or more of the following;
more optionallyOne or more of the following.
The film forming additive can form film on the negative electrode preferentially, reduce the loss of active lithium and further improve the performance of the battery.
In any embodiment, the film forming additive is optionally present in an amount of 0.5 to 20%, optionally 1 to 10%, more optionally 1 to 5%, based on the total weight of the first solvent and the second solvent.
In any embodiment, the film-forming additive optionally comprises 0.5 to 3 percent0.5-3%And 0.5-3%Or 0.5-3%Based on the total weight of the first solvent and the second solvent.
When the electrolyte includes the above-described film-forming additive in the amount, it is advantageous to further improve the storage property and cycle property of the secondary battery.
In any embodiment, optionally, the core further includes a doping element, where the doping element is selected from one or more of W, nb, sb, ti, zr, la, ce, S, and optionally one or more of W, nb.
The doping of the element is advantageous to improve the electrochemical properties of the positive electrode active material, thereby improving the electrochemical properties of the corresponding secondary battery.
In any embodiment, the doping element is optionally present in an amount of 0.05% -5%, optionally 0.1-2%, based on the total weight of the core.
In any embodiment, optionally, the particles of the positive electrode active material are monocrystalline or monocrystalline-like.
When the positive electrode active material is monocrystalline, the active material is not easy to break, the probability of exposing a new surface can be reduced, side reactions of the electrolyte are reduced, and the stability of the electrolyte is improved.
In any embodiment, the particle size of the positive electrode active material is optionally 1 to 20 μm, optionally 3 to 15 μm.
When the particle diameter of the positive electrode active material is within the above range, it is advantageous to avoid an increase in process energy consumption due to an excessively large particle diameter, and to deteriorate the processability of the positive electrode sheet.
In any embodiment, optionally, the electrolyte has an acidity of 50ppm or less and each solvent used has a purity of 99.9% or more.
When the acidity and purity of the electrolyte are within the above ranges, the electrolyte has good stability, and side reactions are not easily generated, thereby being advantageous to improve the cycle performance of the secondary battery.
A second aspect of the present application provides a battery module comprising the secondary battery of the first aspect of the present application. The battery module may be manufactured using a method for manufacturing the battery module, which is generally used in the art.
A third aspect of the present application provides a battery pack comprising the battery module of the second aspect of the present application. The battery pack may be manufactured using a method for manufacturing a battery pack generally used in the art.
A fourth aspect of the present application provides an electric device including at least one selected from the secondary battery of the first aspect of the present application, the battery module of the second aspect of the present application, or the battery pack of the third aspect of the present application.
In the secondary battery described herein, the positive electrode active material includes a core and a coating material coated on the surface of the core, wherein the weight ratio of the coating material to the core is 1:5-100. The proper weight ratio of the coating and the inner core is beneficial to ensuring that the coating effectively reduces direct contact between the inner core material and the electrolyte, thereby reducing interface side reaction, improving storage performance and cycle performance of the secondary battery, and avoiding deterioration of dynamic performance of the secondary battery due to excessive coating. In addition, the coating is also a fast ion conductor, and the capacity of the whole positive electrode active material is not obviously reduced, so that the high energy density of the secondary battery is facilitated. In addition, the electrolyte in the secondary battery comprises the first solvent selected from the fluorinated solvents, which is beneficial to improving the fluorinated degree of the electrolyte, improving the compatibility of the electrolyte with the anode and the cathode, reducing the damage of the electrolyte to the anode and the cathode materials, and further improving the storage performance and the cycle performance of the secondary battery.
The battery module, the battery pack, and the power consumption device of the present application include the secondary battery provided by the present application, and thus have at least the same advantages as the secondary battery.
Fig. 1 is a schematic view of a secondary battery according to an embodiment of the present application.
Fig. 2 is an exploded view of the secondary battery according to an embodiment of the present application shown in fig. 1.
Fig. 3 is a schematic view of a battery module according to an embodiment of the present application.
Fig. 4 is a schematic view of a battery pack according to an embodiment of the present application.
Fig. 5 is an exploded view of the battery pack of the embodiment of the present application shown in fig. 4.
Fig. 6 is a schematic view of an electric device in which the secondary battery according to an embodiment of the present application is used as a power source.
Reference numerals illustrate:
1, a battery pack; 2, upper box body; 3, lower box body; 4, a battery module; 5 a secondary battery; 51 a housing; 52 electrode assembly; 53 roof assembly
Hereinafter, embodiments of the secondary battery, the battery module, the battery pack, and the power consumption device of the present application are specifically disclosed with reference to the accompanying drawings as appropriate. However, unnecessary detailed description may be omitted. For example, detailed descriptions of well-known matters and repeated descriptions of the actual same structure may be omitted. This is to avoid that the following description becomes unnecessarily lengthy, facilitating the understanding of those skilled in the art. Furthermore, the drawings and the following description are provided for a full understanding of the present application by those skilled in the art, and are not intended to limit the subject matter recited in the claims.
The "range" disclosed herein is defined in terms of lower and upper limits, with a given range being defined by the selection of a lower and an upper limit, the selected lower and upper limits defining the boundaries of the particular range. Ranges that are defined in this way can be inclusive or exclusive of the endpoints, and any combination can be made, i.e., any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a particular parameter, it is understood that ranges of 60-110 and 80-120 are also contemplated. Furthermore, if the minimum range values 1 and 2 are listed, and if the maximum range values 3,4 and 5 are listed, the following ranges are all contemplated: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In this application, unless otherwise indicated, the numerical range "a-b" represents a shorthand representation of any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" have been listed throughout, and "0-5" is simply a shorthand representation of a combination of these values. When a certain parameter is expressed as an integer of 2 or more, it is disclosed that the parameter is, for example, an integer of 2, 3,4, 5, 6, 7, 8, 9, 10, 11, 12 or the like.
All embodiments and alternative embodiments of the present application may be combined with each other to form new solutions, unless specifically stated otherwise.
All technical features and optional technical features of the present application may be combined with each other to form new technical solutions, unless specified otherwise.
All steps of the present application may be performed sequentially or randomly, preferably sequentially, unless otherwise indicated. For example, the method comprises steps (a) and (b), meaning that the method may comprise steps (a) and (b) performed sequentially, or may comprise steps (b) and (a) performed sequentially. For example, the method may further include step (c), which means that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), may include steps (a), (c) and (b), may include steps (c), (a) and (b), and the like.
Reference herein to "comprising" and "including" means open ended, as well as closed ended, unless otherwise noted. For example, the terms "comprising" and "comprises" may mean that other components not listed may be included or included, or that only listed components may be included or included.
The term "or" is inclusive in this application, unless otherwise specified. For example, the phrase "a or B" means "a, B, or both a and B. More specifically, either of the following conditions satisfies the condition "a or B": a is true (or present) and B is false (or absent); a is false (or absent) and B is true (or present); or both A and B are true (or present).
In the present application, the term "full charge state" refers to a state when the secondary battery is charged to the upper limit cutoff voltage. Similarly, the term "initial full charge state" refers to a state in which the secondary battery is charged to the upper limit cutoff voltage when the preparation of the secondary battery is completed and manganese element is not included in the electrolyte.
It should be noted that, in the present application, the term "stability factor of the protective layer" may be further subdivided into "stability factor of the static protective layer" and "stability factor of the dynamic protective layer", which are different in that a freshly prepared secondary battery is used when measuring the stability factor e1 of the static protective layer, and the secondary battery used when measuring the stability factor e2 of the dynamic protective layer is not limited, and may be a freshly prepared secondary battery or a secondary battery after a period of use.
The inventors have found in practical operation that when the secondary battery is operated at a high voltage such as 4.2V or more, the elution of the transition metal in the positive electrode active material is exacerbated, thereby deteriorating the storage performance and cycle performance of the secondary battery. The inventor finds that when the positive electrode active material comprises an inner core and a coating substance coating the surface of the inner core after a large number of experiments, and the weight ratio of the coating substance to the inner core is 1:5-100, the stability of the secondary battery under the high-voltage working condition can be effectively improved, so that the storage performance and the cycle performance of the secondary battery are improved. In addition, when the electrolyte comprises a first solvent selected from fluorinated solvents, the compatibility of the electrolyte with the anode and the cathode can be improved, the stability of the secondary battery under the high-voltage working condition is further improved, and the performance of the secondary battery is improved.
The inventors have found after further intensive studies that when the manganese ion dissolution coefficient or the protective layer stability coefficient of the positive electrode sheet satisfies a certain condition, the stability of the secondary battery can be further remarkably improved, thereby improving the storage performance and the cycle performance of the secondary battery.
Secondary battery
A first aspect of the present application provides a secondary battery comprising a positive electrode tab, a negative electrode tab, a separator, and an electrolyte, wherein
The positive electrode plate comprises a positive electrode active material, wherein the positive electrode active material comprises a core and a coating, and the manganese content of the core is more than or equal to 25 percent based on the weight of the core; the coating is coated on the surface of the inner core and comprises one or more of oxides, hydroxides or oxysalts of an element X, wherein the element X is selected from one or more of Al, B or P, and the weight ratio of the coating to the inner core is 1:5-100, and can be 1:16-100;
the electrolyte comprises a first solvent selected from one or more of a fluorocarbonate, a fluorocarboxylate, a fluorosulfone, a fluoroether, or a fluorobenzene.
In the secondary battery described herein, the positive electrode active material includes a core and a coating material coated on the surface of the core, wherein the weight ratio of the coating material to the core is 1:5-100. The proper weight ratio of the coating and the inner core is beneficial to ensuring that the coating effectively reduces direct contact between the inner core material and the electrolyte, thereby reducing interface side reaction, improving storage performance and cycle performance of the secondary battery, and avoiding deterioration of dynamic performance of the secondary battery due to excessive coating. In addition, the coating is also a fast ion conductor, and the capacity of the whole positive electrode active material is not obviously reduced, so that the high energy density of the secondary battery is facilitated. In addition, the electrolyte in the secondary battery comprises the first solvent selected from the fluorinated solvents, which is beneficial to improving the fluorinated degree of the electrolyte, improving the compatibility of the electrolyte with the anode and the cathode, reducing the damage of the electrolyte to the anode and the cathode materials, and further improving the storage performance and the cycle performance of the secondary battery.
In some embodiments, optionally, the positive electrode sheet has a manganese ion dissolution coefficient k less than or equal to 0.035%, optionally k less than or equal to 0.017%, and more optionally k less than or equal to 0.01%, where the manganese ion dissolution coefficient refers to the weight percentage of manganese ions in the electrolyte after the positive electrode sheet in a fully charged state is stored at 60 ℃ for 48 hours with the electrolyte (electrolyte injection coefficient of 5 g/Ah).
When the manganese ion dissolution coefficient of the positive electrode sheet meets the conditions, the interface stability of the positive electrode can be obviously improved, the interface side reaction is reduced, the stability of the secondary battery is improved, and the storage performance and the cycle performance of the secondary battery are further improved.
In some embodiments, optionally, the static protection layer stability factor of the positive electrode sheet is 54% or less than or equal to e1 or less than or equal to 100%, optionally 70% or less than or equal to e1 or less than or equal to 100%, and more optionally 85% or less than or equal to e1 or less than or equal to 100%, where the static protection layer stability factor refers to a ratio of a content of element X remaining in a positive electrode film layer to a content of element X included in the positive electrode film layer when the positive electrode sheet is in an initial full-charge state after the positive electrode sheet is stored at 60 ℃ for 48 hours together with the electrolyte.
The stability coefficient e1 of the static protective layer can better reflect the degree of the element X in the positive electrode film layer dissolved into the electrolyte. When the stability coefficient of the static protection layer meets the above conditions, the secondary battery is favorable to have good stability, and the storage performance and the cycle performance of the secondary battery are improved.
It should be noted that, after the secondary battery is used for a period of time, if the content of the element X in the positive electrode film layer at the initial full charge state of the secondary battery is not known in advance, the obtaining of the static protection layer stability coefficient e1 becomes difficult. Alternatively, the dynamic protective layer stability factor e2 can be used to measure the rate at which element X in the positive electrode film dissolves into the electrolyte. The larger the dynamic protective layer stability coefficient e2 is, the smaller the dissolution rate of the element X in the positive electrode film layer into the electrolyte is, which indicates that the stability of the secondary battery is better; conversely, the greater the dissolution rate, the poorer the stability of the secondary battery.
In some embodiments, optionally, the dynamic protection layer stability factor of the positive electrode sheet is 20% or less than or equal to e2 and less than or equal to 100%, optionally 50% or less than or equal to e2 and less than or equal to 100%, and more optionally 70% or less than or equal to e2 and less than or equal to 100%, and the dynamic protection layer stability factor refers to a ratio of a content of element X remaining in a positive electrode film layer after the positive electrode sheet in a full charge state is stored at 60 ℃ for 48 hours together with the electrolyte, to a content of element X included in the positive electrode film layer before the above storage.
When the dynamic protection layer stability coefficient e2 is within the above range, the secondary battery has better stability, which is beneficial to improving the storage performance and the cycle performance of the secondary battery.
In general, a secondary battery includes a positive electrode tab, a negative electrode tab, an electrolyte, and a separator. During the charge and discharge of the battery, active ions are inserted and extracted back and forth between the positive electrode plate and the negative electrode plate. The electrolyte plays a role in ion conduction between the positive electrode plate and the negative electrode plate. The isolating film is arranged between the positive pole piece and the negative pole piece, and mainly plays a role in preventing the positive pole piece and the negative pole piece from being short-circuited, and meanwhile ions can pass through the isolating film. The positive electrode sheet, the negative electrode sheet, the electrolyte and the separator described in the present application are described below, respectively.
[ Positive electrode sheet ]
The positive pole piece comprises a positive current collector and a positive film layer arranged on at least one surface of the positive current collector, wherein the positive film layer comprises a positive active material.
As an example, the positive electrode current collector has two surfaces opposing in its own thickness direction, and the positive electrode film layer is provided on either one or both of the two surfaces opposing the positive electrode current collector.
In some embodiments, the positive current collector may employ a metal foil or a composite current collector. For example, as the metal foil, aluminum foil may be used. The composite current collector may include a polymeric material base layer and a metal layer formed on at least one surface of the polymeric material base layer. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel alloy, titanium alloy, silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
In some embodiments, optionally, the inner core in the positive electrode active material described herein is selected from LiM p Mn 2-p O 4 、LiN q Mn 1-q PO 4 Or Li (lithium) 1+t Mn 1-w L w O 2+t Wherein 0.ltoreq.p.ltoreq.1, 0.ltoreq.q.ltoreq.0.5, 0.ltoreq.t.ltoreq.1, 0.ltoreq.w.ltoreq.0.5, M, N, L each independently represent one or more of Ni, co, fe, cr, V, ti, zr, la, ce, rb, P, W, nb, mo, sb, B, al, si;
more optionally LiM p Mn 2-p O 4 Or Li (lithium) 1+t Mn 1-w L w O 2+t One or more of the following;
more optionally LiNi 0.5 Mn 1.5 O 4 、LiNi 0.5 Co 0.2 Mn 0.3 O 2 、Li 2 MnO 3 、LiMnPO 4 One or more of the following.
When the core material of the secondary battery is selected from the above types, it is advantageous to increase the energy density of the secondary battery, reduce the manufacturing cost, and reduce environmental pollution.
In some embodiments, optionally, the coating in the positive electrode active material described herein is selected from the group consisting of aluminum oxide, boron oxide, borate, a a+ x [BO 3 ] 3- y Phosphate, i.e. A a+ x [PO 4 ] 3- y Or aluminates, i.e. A a+ x [AlO 2 ] 1- z Wherein a represents one or more of Li, na, K, rb, cs, mg, ca, ba, ni, fe, co, ti, al, cr, V, nb, W, wherein each compound is electrically neutral, a, x, y or z is selected from 1, 2 or 3;
can be selected from Al 2 O 3 、B 2 O 3 、Li 3 BO 3 、Li 3 PO 4 、Na 3 PO 4 Or LiAlO 2 One or more of the following.
When the coating is selected from the above materials, it is advantageous to reduce elution of transition metals and interfacial side reactions, thereby improving battery performance. In addition, the coating is a fast ion conductor, and the capacity of the whole positive electrode active material is not obviously reduced, so that the high energy density of the secondary battery is facilitated.
In some embodiments, the content of element X in the positive electrode film layer is optionally 0.05% to 5.35%, optionally 0.1% to 1.61%, more optionally 0.24% to 1.61%, based on the total weight of the positive electrode active material.
When the content of the element X in the positive electrode film layer is in the range, the direct contact between the core material and the electrolyte can be effectively reduced, the side reaction is reduced, and the dissolution of manganese ions is reduced, so that the storage performance and the cycle performance of the secondary battery are improved.
In some embodiments, optionally, a doping element is further included in the core, the doping element being selected from one or more of W, nb, sb, ti, zr, la, ce, S, optionally W, nb.
The doping of the element is advantageous to improve the electrochemical properties of the positive electrode active material, thereby improving the electrochemical properties of the corresponding secondary battery.
In some embodiments, the doping element is optionally present in an amount of 0.05% -5%, optionally 0.1-2%, based on the total weight of the core.
In some embodiments, optionally, the particles of the positive electrode active material are monocrystalline or monocrystalline-like.
When the positive electrode active material is monocrystalline, the active material is not easy to break, the probability of exposing a new surface can be reduced, side reactions of the electrolyte are reduced, and the stability of the electrolyte is improved.
In some embodiments, the particle size of the positive electrode active material is optionally 1 to 20 μm, optionally 3 to 15 μm. The particle diameter of the positive electrode active material can be determined by a method generally used in the art, and for example, reference can be made to standard GB/T19077-2016/ISO 13320: 2009.
When the particle diameter of the positive electrode active material is within the above range, it is advantageous to avoid an increase in process energy consumption due to an excessively large particle diameter, and to deteriorate the processability of the positive electrode sheet.
In some embodiments, the positive electrode active material may optionally comprise 85-99%, alternatively 93-97%, of the total weight of the positive electrode film layer. For example, the positive electrode active material may account for 85%, 90%, 95.5%, or 97% of the total weight of the positive electrode film layer.
In some embodiments, the positive electrode film layer optionally further comprises a binder. As an example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluoroacrylate resin.
In some embodiments, the binder may optionally comprise 0.1 to 3.5%, alternatively 0.5 to 2.5%, of the total weight of the positive electrode film layer.
In some embodiments, the positive electrode film layer further optionally includes a conductive agent. As an example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.
In some embodiments, the conductive agent may optionally comprise 0.05-5%, alternatively 0.5-3%, of the total weight of the positive electrode film layer.
In some embodiments, the positive electrode sheet may be prepared by: dispersing the above components for preparing the positive electrode sheet, such as the positive electrode active material, the conductive agent, the binder and any other components, in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; and (3) coating the positive electrode slurry on a positive electrode current collector, and obtaining a positive electrode plate after the procedures of drying, cold pressing and the like.
[ negative electrode sheet ]
The negative electrode plate comprises a negative electrode current collector and a negative electrode film layer arranged on at least one surface of the negative electrode current collector, wherein the negative electrode film layer comprises a negative electrode active material.
As an example, the anode current collector has two surfaces opposing in its own thickness direction, and the anode film layer is provided on either one or both of the two surfaces opposing the anode current collector.
In some embodiments, the negative electrode current collector may employ a metal foil or a composite current collector. For example, as the metal foil, copper foil may be used. The composite current collector may include a polymeric material base layer and a metal layer formed on at least one surface of the polymeric material base material. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel alloy, titanium alloy, silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
In some embodiments, the anode active material may employ an anode active material for a battery, which is well known in the art. As an example, the anode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, and the like. The silicon-based material may be at least one selected from elemental silicon, silicon oxygen compounds, silicon carbon composites, silicon nitrogen composites, and silicon alloys. The tin-based material may be at least one selected from elemental tin, tin oxide, and tin alloys. However, the present application is not limited to these materials, and other conventional materials that can be used as a battery anode active material may be used. These negative electrode active materials may be used alone or in combination of two or more.
In some embodiments, the negative electrode film layer further optionally includes a binder. The binder may be at least one selected from Styrene Butadiene Rubber (SBR), polyacrylic acid (PAA), sodium Polyacrylate (PAAs), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium Alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).
In some embodiments, the negative electrode film layer further optionally includes a conductive agent. The conductive agent is at least one selected from superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.
In some embodiments, the negative electrode film layer may optionally further include other adjuvants, such as thickening agents (e.g., sodium carboxymethyl cellulose (CMC-Na)), and the like.
In some embodiments, the negative electrode sheet may be prepared by: dispersing the above components for preparing the negative electrode sheet, such as a negative electrode active material, a conductive agent, a binder and any other components, in a solvent (e.g., deionized water) to form a negative electrode slurry; and coating the negative electrode slurry on a negative electrode current collector, and obtaining a negative electrode plate after the procedures of drying, cold pressing and the like.
[ electrolyte ]
The electrolyte plays a role in ion conduction between the positive electrode plate and the negative electrode plate. Typically, the electrolyte includes an electrolyte salt and a solvent.
In some embodiments, optionally, the first solvent in the electrolyte described herein is selected fromWherein R is one or more of 1 、R 3 、R 5 And R is 13 Independently of one another selected from C 1 To C 6 Fluoroalkanes, R 2 、R 4 、R 6 、R 14 、R 15 And R is 16 Independently of one another selected from C 1 To C 6 Alkanes or C 1 To C 6 Fluoroalkanes, R 7 To R 12 Independently of one another selected from C 1 To C 6 Fluoroalkanes, fluorine or hydrogen, wherein R 7 To R 12 At least one of them is selected from fluorine or fluorinated alkanes, R 15 And R is 16 At least one of them is selected from C 1 To C 6 A fluoroalkane;
can be selected as One or more of the following.
When the first solvent is contained in the electrolyte, the stability of the electrolyte is favorably improved, and the compatibility of the electrolyte with the anode and the cathode is improved, so that the storage performance and the cycle performance of the secondary battery are improved.
In some embodiments, optionally, the electrolyte further comprises a second solvent selected from one or more of a non-fluorinated carbonate, a non-fluorinated carboxylate, a non-fluorinated ether, or a non-fluorinated sulfone;
can be selected asWherein R is one or more of 1 ’、R 2 ’、R 3 ’、R 13 ’、R 14 ' and R 16 ' are independently selected from C 1 To C 6 Alkanes, R 4 ' and R 15 ' are independently selected from C 1 To C 6 Alkanes or hydrogen;
more preferably one or more of methyl ethyl carbonate, dimethyl carbonate, diethyl carbonate, ethylene carbonate, propylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, and propyl propionate.
When the first solvent and the second solvent are both selected from the solvents, the solvents can form a special solvation structure with lithium salt in the electrolyte, which is beneficial to reducing side reactions of the solvents on the surfaces of the anode and the cathode and prolonging the service life of the secondary battery.
In some embodiments, the first solvent content y1 is optionally 10-100%, optionally 40-100%, more optionally 80-100%, based on the total weight of the first solvent and the second solvent. As an example, the content y1 of the first solvent may be 40%, 70%, 80%, 95% or 100%.
In some embodiments, the second solvent is optionally present in an amount y2 of 0-90%, optionally 0-60%, more optionally 0-20%, based on the total weight of the first solvent and the second solvent. As an example, the content y2 of the second solvent may be 0%, 5%, 20%, 30% or 60%.
When the contents of the first solvent and the second solvent are within the above-described ranges, it is advantageous to further improve the stability of the electrolyte, and to improve the storage performance and the cycle performance of the secondary battery.
In some embodiments, optionally, the sum of the weights of the first solvent and the second solvent is 60-90%, optionally 60-87.5%, of the total weight of the electrolyte of the present application.
When the sum of the weights of the first solvent and the second solvent accounts for the weight percentage of the electrolyte in the application, the stability of the electrolyte is further improved.
In some embodiments, optionally, the content y1 of the first solvent and the content y2 of the second solvent satisfy: y1/y2 is more than or equal to 0.66, optionally y1/y2 is more than or equal to 2.33, and more optionally y1/y2 is more than or equal to 4.
When the content y1 of the first solvent and the content y2 of the second solvent meet the above relation, the electrolyte has better electrochemical stability, which is helpful to further improve the compatibility of the electrolyte with the anode and the cathode, reduce side reaction and improve the storage performance and the cycle performance of the secondary battery.
In some embodiments, optionally, the content y1 of the first solvent and the content y2 of the second solvent satisfy: y1 x y 2/(y1+y2) is 0 or less and 0.25 or less, alternatively 0 or less and y1 x y 2/(y1+y2) is 0.16 or less.
When the content y1 of the first solvent and the content y2 of the second solvent satisfy the above-described relationship, further improvement of the stability of the electrolyte is facilitated, thereby improving the storage performance and the cycle performance of the secondary battery.
In some embodiments, optionally, the electrolyte salt in the electrolyte may be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium difluorosulfonimide, lithium bistrifluoromethanesulfonimide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalato borate, lithium difluorodioxaato phosphate, and lithium tetrafluorooxalato phosphate.
In some embodiments, the lithium salt is optionally present in a concentration of 5 to 50 wt%, alternatively 8 to 40 wt%, based on the total weight of the electrolyte.
When the electrolyte comprises the lithium salt with the concentration, the viscosity of the electrolyte is moderate, which is beneficial to improving the conductivity of the electrolyte and further improving the performance of the secondary battery. However, when the concentration of the lithium salt of the electrolyte is too high, the overall concentration of the electrolyte increases, the degree of dissociation of the salt in the electrolyte decreases, and the viscosity of the electrolyte increases, which in turn leads to a decrease in the conductivity of the electrolyte.
In some embodiments, optionally, the electrolyte further comprises a film-forming additive selected from one or more of a chain or cyclic sulfate, a chain or cyclic sulfonate, a chain or cyclic carbonate, a polycyclic sulfate, or a polycyclic sulfonate;
can be selected as One or more of the following;
more optionallyOne or more of the following.
The film forming additive can form film on the negative electrode preferentially, reduce the loss of active lithium, and further improve the storage performance and the cycle performance of the secondary battery.
In some embodiments, the film-forming additive is optionally present in an amount of 0.5 to 20%, optionally 1 to 10%, more optionally 1 to 5%, based on the total weight of the first solvent and the second solvent.
In some embodiments, optionally, the film-forming additive comprises 0.5-3%0.5-3%And 0.5-3%Or 0.5-3%Based on the total weight of the first solvent and the second solvent.
When the electrolyte includes the above-described film forming additive in the amount, it is advantageous to further improve the stability of the electrolyte, thereby further improving the storage performance and cycle performance of the corresponding secondary battery.
In some embodiments, the electrolyte of the present application optionally further comprises other functional additives, which may be any additive known in the art that is suitable in the context of the present application. As an example, the electrolyte further includes at least one of a flame retardant additive, an overcharge preventing additive, and a conductive additive. The inclusion of the above additives in the electrolyte can further improve the performance of the electrolyte.
In some embodiments, optionally, the electrolyte has an acidity of 50ppm or less and each solvent used has a purity of 99.8% or more.
When the acidity and purity of the electrolyte are within the above ranges, the electrolyte has good stability, and side reactions are not easily generated, thereby being advantageous to improve the cycle performance of the secondary battery.
It should be noted that the acidity of the electrolyte in the present application can be tested by methods commonly used in the art, and reference may be made specifically to HG/T4067-2015, by dropping the free acid in the electrolyte using a triethylamine standard solution.
In some embodiments, the electrolyte in the secondary battery described herein may have a fill factor of 1.8-4g/Ah, optionally 2.4-3.2g/Ah. As an example, when the injection coefficient of the secondary battery is 2.8g/Ah and the cell capacity is designed to be 3Ah, the injection amount is 2.83g=8.4 g.
It is to be noted that the electrolyte described in the present application may be prepared by a method generally used by those skilled in the art, as understood by those skilled in the art. For example, the first solvent, the second solvent, the lithium salt, the film-forming additive, other additives and the like can be mixed and stirred uniformly according to a certain proportion under the protection of inert gas, so that the electrolyte can be prepared.
[ isolation Membrane ]
In some embodiments, a separator is further included in the secondary battery. The type of the separator is not particularly limited, and any known porous separator having good chemical stability and mechanical stability may be used.
In some embodiments, the material of the isolating film may be at least one selected from glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride. The separator may be a single-layer film or a multilayer composite film, and is not particularly limited. When the separator is a multilayer composite film, the materials of the respective layers may be the same or different, and are not particularly limited.
A second aspect of the present application provides a battery module comprising the secondary battery according to the first aspect of the present application.
A third aspect of the present application provides a battery pack comprising the battery module of the second aspect of the present application.
A fourth aspect of the present application provides an electric device comprising at least one of the secondary battery of the first aspect, the battery module of the second aspect, or the battery pack of the third aspect of the present application. The secondary battery, the battery module, or the battery pack may be used as a power source of the power consumption device, and may also be used as an energy storage unit of the power consumption device. The power utilization device may include mobile devices (e.g., cell phones, notebook computers, etc.), electric vehicles (e.g., electric-only vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc., but is not limited thereto.
As the electricity consumption device, a secondary battery, a battery module, or a battery pack may be selected according to the use requirements thereof.
The secondary battery, the battery module, the battery pack, and the electric device of the present application will be described below with reference to the drawings as appropriate.
In some embodiments, the positive electrode tab, the negative electrode tab, and the separator may be manufactured into an electrode assembly through a winding process or a lamination process.
In some embodiments, the secondary battery may include an outer package. The outer package may be used to encapsulate the electrode assembly and electrolyte described above.
In some embodiments, the outer package of the secondary battery may be a hard case, such as a hard plastic case, an aluminum case, a steel case, or the like. The exterior package of the secondary battery may also be a pouch type pouch, for example. The material of the flexible bag may be plastic, and examples of the plastic include polypropylene, polybutylene terephthalate, and polybutylene succinate.
The shape of the secondary battery is not particularly limited in the present application, and may be cylindrical, square, or any other shape. For example, fig. 1 is a secondary battery 5 of a square structure as one example.
In some embodiments, referring to fig. 2, the outer package may include a housing 51 and a cover 53. The housing 51 may include a bottom plate and a side plate connected to the bottom plate, where the bottom plate and the side plate enclose a receiving chamber. The housing 51 has an opening communicating with the accommodation chamber, and the cover plate 53 can be provided to cover the opening to close the accommodation chamber. The positive electrode tab, the negative electrode tab, and the separator may be formed into the electrode assembly 52 through a winding process or a lamination process. The electrode assembly 52 is enclosed in the accommodating chamber. The electrolyte is impregnated in the electrode assembly 52. The number of electrode assemblies 52 included in the secondary battery 5 may be one or more, and those skilled in the art may select according to specific practical requirements.
In some embodiments, the secondary batteries may be assembled into a battery module, and the number of secondary batteries included in the battery module may be one or more, and the specific number may be selected by one skilled in the art according to the application and capacity of the battery module.
Fig. 3 is a battery module 4 as an example. Referring to fig. 3, in the battery module 4, a plurality of secondary batteries 5 may be sequentially arranged in the longitudinal direction of the battery module 4. Of course, the arrangement may be performed in any other way. The plurality of secondary batteries 5 may be further fixed by fasteners.
Alternatively, the battery module 4 may further include a case having an accommodating space in which the plurality of secondary batteries 5 are accommodated.
In some embodiments, the above battery modules may be further assembled into a battery pack, and the number of battery modules included in the battery pack may be one or more, and a specific number may be selected by those skilled in the art according to the application and capacity of the battery pack.
Fig. 4 and 5 are battery packs 1 as an example. Referring to fig. 4 and 5, a battery case and a plurality of battery modules 4 disposed in the battery case may be included in the battery pack 1. The battery box includes an upper box body 2 and a lower box body 3, and the upper box body 2 can be covered on the lower box body 3 and forms a closed space for accommodating the battery module 4. The plurality of battery modules 4 may be arranged in the battery box in any manner.
Fig. 6 is an electrical device as an example. The electric device is a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle or the like. In order to meet the high power and high energy density requirements of the secondary battery by the power consumption device, a battery pack or a battery module may be employed.
As another example, the device may be a cell phone, tablet computer, notebook computer, or the like. The device is generally required to be light and thin, and a secondary battery can be used as a power source.
Examples
Hereinafter, embodiments of the present application are described. The embodiments described below are exemplary only for the purpose of illustrating the present application and are not to be construed as limiting the present application. The examples are not to be construed as limiting the specific techniques or conditions described in the literature in this field or as per the specifications of the product. The reagents or apparatus used were conventional products commercially available without the manufacturer's attention.
The polyvinylidene fluoride (PVDF) used in the examples herein had a weight average molecular weight of about 90 ten thousand, and the purity of each solvent used in the examples herein was greater than 99.9%. It should be noted that the materials used in the examples of the present application are based on the weight excluding the crystal water unless specifically stated otherwise.
Example 1
Preparation of positive electrode active material
LiNi is added to 0.5 Mn 1.5 O 4 Adding into proper deionized water, and stirring and mixing uniformly to form suspension. Li is then added to the suspension 3 PO 4 And fully and uniformly stirring. Then filtering and drying to obtain solid powder. Treating the obtained solid powder at 650deg.C for 8 hr to obtain Li-coated powder 3 PO 4 LiNi of (C) 0.5 Mn 1.5 O 4 . Wherein the content of the P element in the coating is 0.50% based on the total weight of the obtained positive electrode active material.
The positive electrode active material preparation method in the comparative example and other examples was the same as described above, except that the kinds of added substances and the contents of the corresponding elements were different.
Preparation of positive electrode plate
Fully stirring and mixing the positive electrode active material obtained in the previous step, carbon black (Super P) serving as a conductive agent and polyvinylidene fluoride (PVDF) serving as a binder in a proper amount of solvent NMP according to the mass ratio of 95.5:2.5:2 to form uniform positive electrode slurry; and uniformly coating the positive electrode slurry on the surface of the positive electrode current collector aluminum foil, and coating both sides. And drying and cold pressing to obtain the positive pole piece. The positive electrode active material loading on one side of the positive electrode current collector was 0.020g/cm 2 。
Preparation of negative electrode plate
Fully stirring and mixing negative electrode active material artificial graphite, conductive agent carbon black (Super P), binder styrene-butadiene rubber and thickener sodium carboxymethyl cellulose in a proper amount of solvent deionized water according to a mass ratio of 96:1:1:2 to form uniform negative electrode slurry; and uniformly coating the negative electrode slurry on the surface of a negative electrode current collector copper foil, and coating one surface. And drying and cold pressing to obtain the negative electrode plate. The negative electrode active material loading on the single side of the negative electrode current collector was 0.008g/cm 2 。
Preparation of electrolyte
In an argon atmosphere glove box (H 2 O＜0.1ppm，O 2 < 0.1 ppm), referring to table 1, various organic solvents were uniformly mixed in the mass ratio shown, and salts and additives shown in table 1 were added and stirred uniformly to obtain an electrolyte of example 1.
Isolation film
A polypropylene film was used as a separator.
Preparation of secondary battery
The positive electrode sheet, the separator and the negative electrode sheet are sequentially stacked, the separator is positioned between the positive electrode sheet and the negative electrode sheet to play a role in separation, the electrode assembly is placed in a battery shell, electrolyte is injected after drying, and the secondary battery of the embodiment 1 is prepared through processes of formation, standing and the like. The size of the obtained secondary battery is 60 multiplied by 130 multiplied by 4mm, the corresponding size of the positive and negative plates is 87 multiplied by 700mm, and the injection coefficient of the electrolyte is 2.8g/Ah.
Examples 2 to 20 and comparative examples 1 to 3
The other conditions of examples 2 to 20 and comparative examples 1 to 3 were the same as example 1 except that the conditions as shown in Table 1 were different.
Related parameter testing method
1. Cell capacity (C) test
At 25 ℃, charging the lithium ion battery to an upper limit cutoff voltage with a constant current of 0.1C, then charging the lithium ion battery to a current of less than 0.05C with the constant voltage, and then discharging the lithium ion battery to a lower limit cutoff voltage with 0.1C to obtain a discharge capacity C (Ah).
2. Manganese ion dissolution coefficient and protective layer stability coefficient test
Lithium ion batteries (2 replicates) were charged at a constant current of 0.1C to an upper cutoff voltage at 25 ℃, then charged at constant voltage to a current of less than 0.05C at that voltage, and then disassembled in a glove box. And soaking the positive electrode plate of one lithium battery with dimethyl carbonate for 1-3 times (the dimethyl carbonate is replaced immediately to be soaked for another time after the single soaking is finished), and then drying and then carrying out element content test to obtain the content of the element X in the positive electrode film layer as X1 by weight.
For the other parallel sample, the positive electrode plate is taken out by a similar method, then added into electrolyte (the composition is shown in table 1) corresponding to 5g/Ah, sealed and placed in a 60 ℃ oven for standing for 48h. And then taking out the corresponding electrolyte in a glove box, then carrying out element content component test, measuring the weight content of manganese ions (manganese elements) in the electrolyte, and dividing the weight of the electrolyte by the weight of the electrolyte to obtain the weight percentage content of the manganese ions (manganese elements) in the electrolyte as y1. Correspondingly, soaking the stored positive electrode plate with dimethyl carbonate for 1h for 3 times (the dimethyl carbonate is replaced immediately for another soaking after the single soaking is completed), and then drying and then carrying out element content test to obtain the content of element X in the positive electrode film layer as X2 by weight. The manganese ion elution coefficient k=y1 of the secondary battery and the protection layer stability coefficient e=x2/x 1.
The static protection layer stability factor e1 and the dynamic protection layer stability factor e2 can be measured by the method for measuring the protection layer stability factor, and the difference is that: the secondary battery used in measuring the static protection layer stability factor e1 is a freshly prepared secondary battery, and the secondary battery used in measuring the dynamic protection layer stability factor e2 is not limited, and may be a freshly prepared secondary battery or a secondary battery after a period of use. The present examples and comparative examples were tested for freshly prepared secondary batteries, and thus the protective layer stability factor in table 1 was the static protective layer stability factor e1.
The manganese ion content in the electrolyte and the manganese element and element X content in the positive electrode film layer are tested by adopting an inductively coupled plasma emission spectrometry, wherein the instrument standard is referred to EPA6010D-2014, the inductively coupled plasma atomic emission spectrometry, JY/T015-1996, the inductively coupled plasma atomic emission spectrometry general rule.
The manganese element content and the element X (B or P) content in the positive electrode film layer can be determined by the following method: and (3) punching the positive electrode plate into small wafers with the radius of 7mm, weighing 6 positive electrode small wafers with the corresponding weight of m1, adding 10ml of aqua regia, heating to fully digest, and then using deionized water to fix the volume to 100ml. And testing the solution by adopting an inductively coupled plasma emission spectrometry to obtain the content of the element X in the 6 corresponding anode small wafers, wherein the content of the element X in the 6 corresponding anode small wafers is m2. In addition, 6 small wafer positive electrode plate substrates (aluminum substrates) with the radius of 7mm are taken, and the mass of the substrate is measured to be m3. The corresponding X element content is x1=m2/(m 1-m 3).
When the element X is aluminum, the method for testing the X content in the positive electrode active material is slightly different, the active material on the surface of the electrode sheet needs to be scraped (note that the aluminum substrate cannot be scraped), the mass of the scraped mixture is measured as m4, and then the mass of X in the mixture is measured as m2 by adopting the same method. The content of the corresponding X element (Al) is m2/m4.
The method for testing the manganese ion content in the electrolyte comprises the following steps: about 1g of the electrolyte is takenAdding 10ml of concentrated HNO into the solution 3 Acid (68% by mass) was then heated at 180 ℃ for 30min, and then the volume was fixed with deionized water to 50ml. And testing the solution by adopting an inductively coupled plasma emission spectrometry, and finally measuring to obtain the content of manganese ions (manganese elements) in the electrolyte by weight, wherein the content of the manganese ions (manganese elements) in the electrolyte by weight is y1 after dividing the content by the mass of the electrolyte.
3. Positive electrode active material gram Capacity test
Charging the secondary battery at a constant current of 0.33C to an upper limit cutoff voltage at 25 ℃, and then charging the secondary battery at a constant voltage to a current of 0.05C; after standing for 5min, the secondary battery is discharged to the lower limit cutoff voltage at a constant current of 0.33C, and the discharge capacity obtained at this time is the initial discharge capacity of the secondary battery.
Initial discharge gram capacity (mAh/g) of the positive electrode active material=initial discharge capacity of the secondary battery/total mass of the positive electrode active material.
4. Cycle performance test of secondary battery
Charging the secondary battery at a constant current of 0.1C to an upper limit cutoff voltage at 45 ℃, and then charging the secondary battery at a constant voltage to a current of 0.05C; after standing for 5min, the secondary battery was discharged to a lower limit cutoff voltage at a constant current of 0.1C, which is a charge-discharge cycle process, and the discharge capacity at this time was the initial discharge capacity of the secondary battery. And (3) circularly charging and discharging the secondary battery according to the method until the discharge capacity after circulation is reduced to 80% of the initial discharge capacity, ending the test, and recording the circle number of the secondary battery at the moment. The higher the number of cycles of the secondary battery, the longer the cycle life expectancy of the secondary battery.
5. Secondary battery storage performance test
The secondary battery was charged at a constant current of 0.1C to an upper limit cutoff voltage at 25C, and then charged at a constant voltage to a current of 0.05C at the cutoff voltage, at which time the secondary battery was in a full charge state. Placing the secondary battery in a full charge state in an environment of 25 ℃ for storage, taking out once every 5 days, and discharging to a lower limit cut-off voltage with a constant current of 0.1C to obtain the discharge amount after being stored for a period of time; and then the secondary battery is fully charged in the mode and then is stored in the environment of 25 ℃ again until the discharge capacity of the secondary battery after being stored is reduced to 80% of the initial discharge capacity, the test is finished, and the total storage days of the secondary battery are recorded. The more days of storage of the secondary battery, the longer the expected life of the secondary battery in room temperature storage.
In each of the above performance tests, the upper limit cutoff voltage was 4.95V and the lower limit cutoff voltage was 3.0V in the examples and comparative examples. The results of the performance tests of examples 1-20 and comparative examples 1-3 are shown in Table 1.
As can be seen from table 1, when the positive electrode active material contains the coating material and the first solvent is contained in the electrolyte, the storage performance and the cycle performance of the corresponding secondary battery are both superior to those of the secondary battery that does not contain the coating material or that does not contain the first solvent. In addition, when the manganese ion dissolution coefficient k of the positive electrode plate is less than or equal to 0.035% or the stability coefficient e1 of the static protection layer is more than or equal to 54%, the storage performance and the cycle performance of the corresponding secondary battery are better. In addition, by adjusting the amounts of the first solvent and the second solvent and the types and amounts of the film forming additives, the storage performance and the cycle performance of the secondary battery can be further improved.
The present application is not limited to the above embodiment. The above embodiments are merely examples, and embodiments having substantially the same configuration and the same effects as those of the technical idea within the scope of the present application are included in the technical scope of the present application. Further, various modifications that can be made to the embodiments and other modes of combining some of the constituent elements in the embodiments, which are conceivable to those skilled in the art, are also included in the scope of the present application within the scope not departing from the gist of the present application.
Claims (23)
- A secondary battery comprises a positive electrode plate, a negative electrode plate, a separation film and an electrolyte, whereinThe positive electrode plate comprises a positive electrode active material, wherein the positive electrode active material comprises a core and a coating, and the manganese content of the core is more than or equal to 25 percent based on the weight of the core; the coating is coated on the surface of the inner core and comprises one or more of oxides, hydroxides or oxysalts of an element X, wherein the element X is selected from one or more of Al, B or P, and the weight ratio of the coating to the inner core is 1:5-100, and can be 1:16-100;the electrolyte comprises a first solvent selected from one or more of a fluorocarbonate, a fluorocarboxylate, a fluorosulfone, a fluoroether, or a fluorobenzene.
- The secondary battery according to claim 1, whereinThe manganese ion dissolution coefficient k of the positive electrode plate is less than or equal to 0.035%, the optional k is less than or equal to 0.017%, and the more optional k is less than or equal to 0.01%, wherein the manganese ion dissolution coefficient refers to the weight percentage of manganese ions in the electrolyte after the positive electrode plate in a full charge state and the electrolyte (electrolyte injection coefficient is 5 g/Ah) are stored for 48 hours at 60 ℃.
- The secondary battery according to claim 1 or 2, whereinThe static protection layer stability coefficient of the positive electrode plate is 54% -100%, optionally 70% -100% e 1% -100% and more optionally 85% -e 1% -100%, and is the ratio of the content of the element X remained in the positive electrode film layer to the content of the element X included in the positive electrode film layer when the positive electrode plate is in the initial full-charge state after the positive electrode plate in the full-charge state and the electrolyte are stored at 60 ℃ for 48 hours.
- The secondary battery according to any one of claims 1 to 3, whereinThe stability coefficient e2 of the dynamic protection layer of the positive electrode plate meets the following conditions: and the dynamic protection layer stability coefficient refers to the ratio of the content of the element X remained in the positive electrode film layer to the content of the element X included in the positive electrode film layer before the storage after the positive electrode plate in a full charge state is stored at 60 ℃ for 48 hours together with the electrolyte, wherein the e2 is more than or equal to 20% and less than or equal to 100%, the e2 is more than or equal to 50% and the e2 is more than or equal to 100% is selected.
- The secondary battery according to any one of claims 1 to 4, whereinThe content of the element X in the positive electrode film layer is 0.05% -5.35%, optionally 0.1% -1.61%, more optionally 0.24% -1.61%, based on the total weight of the positive electrode active material.
- The secondary battery according to any one of claims 1 to 5, whereinThe inner core is selected from LiM p Mn 2-p O 4 、LiN q Mn 1-q PO 4 Or Li (lithium) 1+t Mn 1-w L w O 2+t Wherein 0.ltoreq.p.ltoreq.1, 0.ltoreq.q.ltoreq.0.5, 0.ltoreq.t.ltoreq.1, 0.ltoreq.w.ltoreq.0.5, M, N, L each independently represent one or more of Ni, co, fe, cr, V, ti, zr, la, ce, rb, P, W, nb, mo, sb, B, al, si;more optionally LiM p Mn 2-p O 4 Or Li (lithium) 1+t Mn 1-w L w O 2+t One or more of the following;more optionally LiNi 0.5 Mn 1.5 O 4 、LiNi 0.5 Co 0.2 Mn 0.3 O 2 、Li 2 MnO 3 、LiMnPO 4 One or more of the following.
- The secondary battery according to any one of claims 1 to 6, wherein the coating is selected from the group consisting of alumina, boron oxide, borate, a a+ x [BO 3 ] 3- y Phosphate, i.e. A a+ x [PO 4 ] 3- y Or aluminates, i.e. A a+ x [AlO 2 ] 1- z Wherein a represents one or more of Li, na, K, rb, cs, mg, ca, ba, ni, fe, co, ti, al, cr, V, nb, W, wherein each compound is electrically neutral, a, x, y or z is selected from 1, 2 or 3;can be selected from Al 2 O 3 、B 2 O 3 、Li 3 BO 3 、Li 3 PO 4 、Na 3 PO 4 Or LiAlO 2 One or more of the following.
- The secondary battery according to any one of claims 1 to 7, whereinThe first solvent is selected from Wherein R is one or more of 1 、R 3 、R 5 And R is 13 Independently of one another selected from C 1 To C 6 Fluoroalkanes, R 2 、R 4 、R 6 、R 14 、R 15 And R is 16 Independently of one another selected from C 1 To C 6 Alkanes or C 1 To C 6 Fluoroalkanes, R 7 To R 12 Independently of one another selected from C 1 To C 6 Fluoroalkanes, fluorine or hydrogen, wherein R 7 To R 12 At least one of them is selected from fluorine or fluorinated alkanes, R 15 And R is 16 At least one of them is selected from C 1 To C 6 A fluoroalkane;can be selected asOne or more of the following.
- The secondary battery according to any one of claims 1 to 8, whereinThe electrolyte further comprises a second solvent, wherein the second solvent is selected from one or more of non-fluorinated carbonates, non-fluorinated carboxylates, non-fluorinated ethers or non-fluorinated sulfones;can be selected asWherein R is one or more of 1 ’、R 2 ’、R 3 ’、R 13 ’、R 14 ' and R 16 ' are independently selected from C 1 To C 6 Alkanes, R 4 ' and R 15 ' are independently selected from C 1 To C 6 Alkanes or hydrogen;more preferably one or more of methyl ethyl carbonate, dimethyl carbonate, diethyl carbonate, ethylene carbonate, propylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, and propyl propionate.
- The secondary battery according to claim 9, wherein the content y1 of the first solvent is 10-100%, optionally 40-100%, more optionally 80-100%, based on the total weight of the first solvent and the second solvent.
- The secondary battery according to any one of claims 9 to 10, wherein the content y2 of the second solvent is 0-90%, optionally 0-60%, more optionally 0-20%, based on the total weight of the first solvent and the second solvent.
- The secondary battery according to claim 11, wherein the content y1 of the first solvent and the content y2 of the second solvent satisfy: y1/y2 is more than or equal to 0.66, optionally y1/y2 is more than or equal to 2.33, and more optionally y1/y2 is more than or equal to 4.
- The secondary battery according to any one of claims 1 to 12, whereinThe electrolyte also comprises a film forming additive which is selected from one or more of chain or cyclic sulfate, chain or cyclic sulfonate, chain or cyclic carbonate, polycyclic sulfate or polycyclic sulfonate;can be selected as One or more of the following;more optionallyOne or more of the following.
- The secondary battery of claim 13, wherein the film forming additive is present in an amount of 0.5-20%, alternatively 1-10%, more alternatively 1-5%, based on the total weight of the first and second solvents.
- The secondary battery according to claim 13 or 14, wherein the film-forming additive comprises 0.5 to 3%0.5-3% And 0.5-3%Or 0.5-3%Based on the total weight of the first solvent and the second solvent.
- The secondary battery according to any one of claims 1 to 15, wherein the core further comprises a doping element therein, the doping element being selected from one or more of W, nb, sb, ti, zr, la, ce, S, optionally W, nb.
- The secondary battery according to claim 16, wherein the content of the doping element is 0.05% -5%, optionally 0.1-2%, based on the total weight of the core.
- The secondary battery according to any one of claims 1 to 17, wherein the particles of the positive electrode active material are single crystals or monocrystalline-like crystals.
- The secondary battery according to any one of claims 1 to 18, wherein the particle diameter of the positive electrode active material is 1 to 20 μm, optionally 3 to 15 μm.
- The secondary battery according to any one of claims 1 to 19, wherein the electrolyte has an acidity of 50ppm or less and each solvent used has a purity of 99.9% or more.
- A battery module comprising the secondary battery according to any one of claims 1 to 20.
- A battery pack comprising the battery module of claim 21.
- An electrical device comprising at least one of the secondary battery of any one of claims 1 to 20, the battery module of claim 21, or the battery pack of claim 22.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| PCT/CN2022/092999 WO2023220856A1 (en) | 2022-05-16 | 2022-05-16 | Secondary battery and battery module comprising same, battery pack, and electrical device |
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| CN117461159A true CN117461159A (en) | 2024-01-26 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN202280040386.1A Pending CN117461159A (en) | 2022-05-16 | 2022-05-16 | Secondary battery, battery module, battery pack, and power consumption device including the same |
Country Status (2)
| Country | Link |
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| CN (1) | CN117461159A (en) |
| WO (1) | WO2023220856A1 (en) |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102394311A (en) * | 2011-11-28 | 2012-03-28 | 东莞新能源科技有限公司 | Lithium ion secondary battery with high energy density |
| JP6207329B2 (en) * | 2013-10-01 | 2017-10-04 | 日立マクセル株式会社 | Positive electrode material for non-aqueous secondary battery and method for producing the same, positive electrode mixture layer for non-aqueous secondary battery using positive electrode material for non-aqueous secondary battery, positive electrode for non-aqueous secondary battery, and non-aqueous secondary battery |
| CN105098177B (en) * | 2014-04-24 | 2018-05-29 | 宁德时代新能源科技股份有限公司 | Secondary lithium battery and preparation method of positive electrode material thereof |
| CN108987680B (en) * | 2017-05-31 | 2020-07-03 | 宁德时代新能源科技股份有限公司 | Lithium ion battery |
| JP7366662B2 (en) * | 2019-09-18 | 2023-10-23 | 太平洋セメント株式会社 | Positive electrode active material composite for lithium ion secondary battery and method for manufacturing the same |
-
2022
- 2022-05-16 WO PCT/CN2022/092999 patent/WO2023220856A1/en unknown
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| WO2023220856A1 (en) | 2023-11-23 |
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